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So who’s behind this and what qualifies us as such big twin experts?Our track record. The authors of this site have built some of the highest performing nitro fuel drag bikes that have ever blessed a quarter mile. Getting a big twin to run consistently over 200mph requires some serious engineering, precision machining, and god given talent. There are less than a handful of Harley-Davidson dealers that employ this kind of mechanical talent, and the lessons we learned on the track can completely translate into performance gains for your factory Harley-Davidson motorcycle.

Some of the articles we publish are product reviews, other articles are designed to give an elementary explanation of basic engine functions, and sometimes we’ll simply brag about an engine kit that was born right here in the Race Department at Harley-Davidson of Salt Lake City. We don’t have comments or never ending debates on what does or doesn’t work. We’ll skip the opinions and stick to the cold hard facts. We own our results and trust in the fact that our Dyno never lies.

Want to learn more? Don’t bother with scheduling appointments to come talk with us, just swing into Harley-Davidson of Salt Lake City and chat with the Race Department. We promise results and we’re always here to chat.

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Harley-Davidsons new Screamin’ Eagle 120ST Engine has been given the 50-state legal certification by CARB rendering the 120ci engine the only “street legal” power plant of that size in all 50 states!

Fits ’10 – ‘15 Touring models, 50-state compliant.

(reference Executive Orders M-005-0208 and G-14-012)

This crate engine allows for a one year Over-the-Counter warranty

No SWR is allowed

Not eligible for Extended Service Plan (ESP) through HDFS

While the other good news of getting the 120ST engine CARB-certified the 2010-2015 Harley-Davidson Touring Models in all 50 states (excluding Twin-Cooled models) is still pending.The Motor Company’s CARB-cert could be a positive sign of things to come for 2016 Touring Models or Custom Vehicle Operations (CVO) models.

Now let’s delve into the meat of the engine. The 120ST is essentially similar to that of the configuration of Harley’s beloved Screamin’ Eagle 120R motor: It features the same 4-5/8-inch stroke with a 4.060-inch bore using the same heads, valve springs, and bearings as the 120R, only the 120ST has been “cammed down a bit changing from the R motor’s SE266 cams [with a lift of .658] to SE259 cams [with a lift of .579],” “This was done in order to be street compliant.”

Developed and tested in Milwaukee, this motor features the finest Screamin’ Eagle components: